IDAPA 35.01.03.131 — USE OF RATIO STUDY OR OTHER METHOD TO TEST FOR EQUALIZATION IN COUNTIES

Section 63-109, Idaho Code
01.
Equalization Ratio Study - Primary Categories Other than Agricultural Land. Each year the
Tax Commission will conduct a ratio study to assist in the equalization of assessments of property within and among
the primary categories, other than agricultural land, established in Rule 130 of these rules. The ratio study is
conducted in accordance with the "Standard on Ratio Studies" and the "Standard on Verification and Adjustment of
Sales" both referenced in Rule 003 of these rules.
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a.
The annual ratio study will test assessments as of January 1 of each year. Assessments are tested
using sales occurring between October 1 of the year preceding the year for which assessments are to be tested and
September 30 of the year for which assessments are tested. Alternate time frames may be used when sales must be
added to improve representativeness, or when an alternate study, as described in Subsection 09 of this rule, is to be
used. Each sale price is adjusted for time and compared to market value for assessment purposes for the year for
which assessments are to be tested. To improve representativeness, the Tax Commission may use sales from extended
time periods, may add or delete sales, and may add appraisals when data is lacking. Equalization ratio studies must
consist of at least five (5) sales and/or appraisals. Sales should be considered as potentially valid if a financial
institution is the seller, provided that criteria found in the Standard on Verification and Adjustment of Sales are met.
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b.
The study will be completed annually in March and notice provided to county official in
accordance with Section 63-109, Idaho Code. For non-agricultural categories, the appropriate ratio study statistical
measure of level is the median. For agricultural land categories, level of assessment is to be determined as described
in Paragraph 131.02.b. of this rule.
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02.
Equalization Study - Agricultural Land. Each year the Tax Commission will conduct a study to
assist in the equalization of assessments of agricultural land. Any such study will analyze agricultural land values
throughout each significant secondary agricultural land category using valuation methods found in Section 63-602K,
Idaho Code, and Rule 617 of these rules. A secondary agricultural land category having at least ten percent (10%) of
the acreage and at least five percent (5%) of the value of the primary agricultural land category is considered
significant.
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a.
County officials will receive notice of the results and compliance in accordance with Section 63-
109, Idaho Code.
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b.
Significant secondary agricultural land categories are subject to preliminary and follow-up studies
of assessment level and are studied based on the valuation methodology described in Rule 617 of these rules. The
preliminary study is a comparison to the prior year's assessed values. The follow-up studies will test the current
year's assessed values and are required when preliminary studies indicate a level of assessment less than ninety
percent (90%) or greater than one hundred ten percent (110%) of market value for assessment purposes. Categories
meeting these criteria, and those categories not considered significant in a county, are in compliance. Level means the
ratio of the median per acre assessed value and the median per acre value for the secondary agricultural land category
determined by the Tax Commission using the valuation methodology found in Rule 617 of these rules.
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c.
Secondary agricultural land categories may also be subject to follow-up studies if the Tax
Commission has received information indicating that county boards of equalization have changed values in such a
way as to produce likely non-compliance.
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03.
Timing and Notification. Notice of improper assessment of any category is to occur when any
category tested for equalization purposes is found out of compliance as described in this Rule. Following the first
Monday in April statutory deadline for notice, additional notice will be provided as follows:
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a.
By the second Monday in May, the Tax Commission will notify county assessors and
commissioners of results of any additional ratio studies requested by county assessors. These studies will be based on
current year assessments.
(7-1-24)
IDAHO ADMINISTRATIVE CODE
IDAPA 35.01.03
State Tax Commission
Property Tax Administrative Rules
Section 131
Page 13
b.
By the fourth Monday in July, the Tax Commission will notify county assessors and commissioners
of the results and compliance status based on follow-up studies as provided in Subsections 05 and 06 of this Rule.
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c.
See Timing and Notification Table at https://tax.idaho.gov.
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04.
Tested for Equalization. Except as provided in Subsection 131.05 of this rule, categories, other
than agricultural land to be tested for equalization purposes, are the primary categories described in Subsection
130.01 of these rules.
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05.
Follow-Up Ratio Study. If the annual ratio study indicates that assessments in any primary
category are out of compliance with the standards of this rule, a follow-up study is required. In addition, if the Tax
Commission is informed that a county board of equalization has implemented changes to assessments, likely
resulting in a category failing compliance with the standards for the current year's assessments, a follow-up study is
also required. A follow-up ratio study tests the assessments for January 1 of the year following the timeframe used in
the preliminary agricultural study or the annual ratio study. The follow-up study uses property sales during the
calendar year immediately preceding that date, unless use of an alternate time frame for sales will provide a more
representative study.
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06.
Notice of Follow-Up Ratio Study. The Tax Commission will notify the county commissioners, the
county board of equalization, and the county assessor of the results of any follow-up study. The notification will
include a description of assessment changes if such changes initiated the follow-up study. The notice will specify the
compliance status of each category and will state whether and why the Tax Commission considers adjusting non-
compliant categories based on the annual or follow-up ratio studies at the State Board of Equalization meeting.
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07.
Use of Ratio Study Results. If the results of any ratio study show, with reasonable statistical
certainty as defined in Subsection 131.11 of this rule, that the assessments are not equalized, the Tax Commission
may, at its meeting pursuant to Section 63-108, Idaho Code, order the county auditor to adjust the value of property in
the non-compliant category or categories or any portion of such category. Any adjustment factor recommended to the
Tax Commission will be calculated by dividing the median level of assessment in the category or categories into one
hundred percent (100%). Except as provided in Subsections 131.02 or 131.08 of this rule, adjustment will not be
considered for any secondary category that does not have at least one (1) observation.
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08.
Exception from Requirement for at Least One (1) Observation for Use of Secondary
Category in Adjusted Value Determination. If the ratio study results warrant an adjustment to the assessed values
of the primary residential category, secondary category 10 will receive a similar adjustment if at least one (1) property
observation occurs in either category 12 or 15. Such adjustment is also warranted to the assessed values in secondary
category 31 if at least one (1) observation occurs in secondary category 34 or 37.
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09.
Use of Alternate Ratio Study. When the follow-up ratio study required by Subsection 131.05 of
this rule does not measure the true assessment level, the Tax Commission may consider adjustments based on the
most recent ratio study or other information relevant to equalization.
(7-1-24)
10.
Submission of Additional Information. Any party may request that the Tax Commission consider
any information or studies relevant to equalization. Such a request will include a description of the information to be
presented and conclusions drawn from the information.
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11.
Reasonable Statistical Certainty. For the purposes of equalization of primary categories other
than agricultural categories, "reasonable statistical certainty" that any primary category is not equalized is found if:
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a.
The median ratio for the category(ies) being tested is less than ninety percent (90%) or greater than
one hundred ten percent (110%) and a ninety percent (90%) two-tailed confidence interval around the median fails to
include ninety percent (90%) or one hundred ten percent (110%); or
(7-1-24)
b.
An eighty percent (80%) two-tailed confidence interval around the median fails to include ninety
IDAHO ADMINISTRATIVE CODE
IDAPA 35.01.03
State Tax Commission
Property Tax Administrative Rules
Section 217
Page 14
percent (90%) or one hundred ten percent (110%) and this failure has continued for the current and most recent two
year's ratio studies on the category(ies).
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12.
Cross References. See Rules 130, 510, 511, 512, and 617.
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